[OpenJDK 2D-Dev] [9] Review Request: 8158072 Need a test for JDK-7172749

Sergey Bylokhov Sergey.Bylokhov at oracle.com
Fri May 27 18:47:43 UTC 2016

Please review the new test for jdk9.
To me the reason of JDK-7172749 [1] falling was curious. So I decided to 
dig into it.

To reproduce the bug the next sequence is necessary:
Thread A
  - create the surface
  - SG2D is created for the surface
  - SG2D.drawLine is called
  - XRRenderer(Pipe).drawLine is called
  - ========= STOP "THREAD A" for a nanoseconds=========

Thread B
  - SG2D is created for the surface create in Thread A
  - SG2D.drawLine is called or any other draw operations.
  - The surface is flushed.

Thread A
  -  ========= RUN "THREAD A" again=========
  - (we still inside XRRenderer(Pipe).drawLine)
  - SG2D.getCompClip() is called, and this caused revalidation of SG2D, 
because it was already flushed. This means that the surface/pipes etc 
are changed, but note we still in the old XRRenderer(PixelDrawPipe) 
which actually should be disposed as well
  - we try to use the new surface and got ClassCastException.
  - After the fix we will start to draw the line again from 
"SG2D.drawLine" above, using new surface and the new PixelDrawPipe.

The interesting thing is how we will work if revalidation will replace 
the surface to the same type(so ClassCastException will not occurred) 
but the pipe will be changed to the new? I cannot prove it but it seems 
that we will draw something to the new surface using the old 
PixelDrawPipe. (But this is only for the record if someone will work on 
this/or similar issues).

And the test which reproduce the bug.

Bug: https://bugs.openjdk.java.net/browse/JDK-8158072
Webrev can be found at: http://cr.openjdk.java.net/~serb/8158072/webrev.00

[1] https://bugs.openjdk.java.net/browse/JDK-7172749

Best regards, Sergey.

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